DESCRIPTION: Although an increased susceptibility to colorectal cancer has been identified in first degree relatives of patients with early onset colorectal cancer, little is known about acceptance of recommended colorectal cancer screening among these intermediate risk individuals. For these individuals, guidelines endorsed by the American Cancer Society and the American Gastroenterological Association recommend colon cancer screening starting a decade earlier than average risk individuals, at the age of 40 years. This purpose of this study is to examine acceptance of colon cancer screening among individuals at intermediate familial risk, as well as their levels of knowledge about colon cancer, colon cancer screening (CRC) and the screening recommendations. The second aim is to develop a greater understanding of psychological and non-psychological reasons for acceptance of colonoscopy. This research is guided by a combination of several models of preventive health behavior: the Health Belief Model, the Transtheoretical Model, and the Dual Process Model. The Dual Process Model was chosen to address the role of emotional response to health threats, which is relevant to individuals at increased risk for cancer because of a family history. The role of other non-attitudinal factors, including physician influence and medical history and status, will also be examined. Participants will be 490 siblings of patients diagnosed with adenocarcinoma of the colon or rectum at Fox Chase Cancer Center or Memorial Sloan-Kettering Cancer Center (MSKCC) between 1992 and 1995. The study will examine adoption of colon cancer screening procedures (fecal occult blood testing [FOBT], flexible sigmoidoscopy, and colonoscopy), knowledge of screening guidelines, and knowledge of colorectal cancer, and identify psychological and non-psychological factors which discriminate between individuals at different stages of readiness regarding adoption of colonoscopy. Prediction of compliance with screening guidelines and intention to undergo screening will also be investigated.